This invention relates generally to hypodermic syringes and seeks to solve the problem of accidental puncture with contaminated needles of hypodermic syringes. The hypodermic syringe, according to the present invention, is adapted so that after it is used and substantially at the end of the plunger stroke, the needle is detached from the syringe barrel and is retracted to within a cavity located in the plunger and out of one's way.
The problems associated with accidental puncture with contaminated hypodermic syringe needles has, in recent times, increased and has become substantially grave. Individuals in various health service organizations, such as nurses and doctors, that use hypodermic syringes, are increasingly under pressure to more quickly perform their duties and, thus, are less likely to be cautious when using hypodermic syringes and from potentially being punctured by a contaminated needle. Further, during emergency situations, it is quite often very difficult to be cautious so as to not be punctured by a contaminated needle. The probability of being punctured is further increased in emergency situations when a patient, for example, is convulsive.
The problem of being scratched or punctured has become yet more grave in view of the advent of the Acquired Immune Deficiency Syndrome (AIDS) spreading and becoming more common. As can be appreciated, a health service worker treating an AIDS patient or a patient having hepatitis, can easily contract either of those diseases should he or she be punctured or scratched by a contaminated needle. Accordingly, a need exists for a hypodermic syringe that retracts or hides a contaminated needle after use so that the user of the hypodermic syringe does not become punctured or scratched by the contaminated needle.
Furthermore, a problem exists in the spreading of AIDS among drug users and, thereafter, to the general population. This problem exists in that drug users tend to share and reuse hypodermic syringe needles thereby contracting AIDS or hepatitis from a contaminated needle previously used by someone affected by AIDS or hepatitis. In addition to the problem of accidental punctures and scratches, there is a need to limit or eliminate the reusability of hypodermic syringes or for making a hypodermic syringe unusable after the original and first use.
Various hypodermic syringes have been developed in the past for preventing accidental punctures and scratches by contaminated needles. For example, U.S. Pat. No. 4,026,287; U.S. Pat. No. 4,675,005; and, U.S. Pat. No. 4,692,156 disclose syringes whereby the needle is withdrawn to within the syringe barrel after use. These syringes include a plunger that attaches to the needle and, by pulling the plunger outwardly from within the syringe barrel, the contaminated needle is pulled into the syringe barrel and out of the user's way. As can be appreciated, these syringe devices are difficult to operate in that at the end of an injection, the user must use both hands to attach the plunger to the needle and, thereafter, withdraw the plunger back pulling the needle to within the syringe barrel. This is not only difficult but also time consuming and potentially impractical in today's health service organizations.
Other hypodermic syringe devices of the past, such as those disclosed in U.S. Pat. No. 4,664,654 and U.S. Pat. No. 4,702,738 utilize guards or sheaths for covering a contaminated needle after use. This, however, requires additional components to be carried on the syringe and also requires additional steps at the end of an injection so as to cover the contaminated needle.
Accordingly, a need exists for a hypodermic syringe that is substantially easy and inexpensive to manufacture and that does not require additional steps during use for the covering or retracting of the contaminated needle. A need exists for a hypodermic syringe that is used in the same fashion as other common hypodermic syringes and, that, automatically retracts and places the contaminated needle out of the way at the end of an injection and with minimal effort by the user. A need further exists for a hypodermic syringe that, upon the first use thereof, substantially renders itself unusable and, thereby, preventing the spread of diseases among drug users that share hypodermic syringe needles.